1. Field of the Invention
The present invention relates to nanolithography and, more specifically, to a method for sculpting two-dimensional and three-dimensional nano-scale patterns using a heatable probe.
2. Description of the Prior Art
Small scale patterning and sculpting of surfaces to produce devices as diverse as semiconductors or biological systems is typically accomplished using one of three methods: (1) optical lithography using projection exposure tools at wavelengths ranging from 365 nm to 13 nm, (2) direct write electron beam lithography, and (3) imprint or embossing lithography.
Optical lithography produces a large volume of micro-scale and nano-scale devices. However, as device dimensions shrink below 100 nm in size, optical lithography becomes increasingly difficult. A major problem with optical lithography is in the fabrication of the photomasks that generate the optical patterns used in forming desired physical patterns. Photomasks are produced using direct write methods employing either laser pattern generators or electron beam exposure tools. As device dimensions shrink, photomasks become prohibitively expensive due to the low yields associated with producing such technically demanding photomasks. Methods that could be used to produce photomasks with lower costs, higher throughputs, or with improved yields could substantially benefit the lithography industry and the many industries that rely upon it.
Although electron beam lithography is a high resolution patterning technique, it is still typically used only in device prototyping and niche applications such as photomask manufacturing. Direct-write electron beam lithography is limited because it uses a serial writing style that limits throughput and also because increasing exposure times are required as feature sizes are reduced and accelerating potentials are increased. Also, due to their highly complex nature, the development and final costs of advanced electron beam patterning systems are extremely high.
Even if all of the lithography challenges were to be overcome, there would still be a need to inspect and repair low-volume, high-value application-specific integrated circuits, particularly at device sizes that cannot be accessed by optical techniques. Once fabricated, integrated circuit chips are not easily post-processed, especially given the high temperatures and harsh chemical conditions that conventional patterning systems expose the chip to. One strategy to post-processing has been complete encapsulation of the circuit elements, but this does not allow the circuit itself to be modified.
The atomic force microscope (AFM) offers significant opportunities to probe and manipulate material at the nanometer scale. The scaling of these probing and manipulating techniques to large arrays of AFM probes may become the technology that enables the practical implementation of nanotechnologies for widespread use. While there are a number of nanometer-scale manufacturing techniques that exploit the AFM, there remain several unmet needs. While sub-100 nm resolution is possible with a number of techniques, the writing speed is a significant challenge, with typical tip speeds in the range 0.1-1 nm/sec. Furthermore, AFM writing techniques offer little three-dimensionality, with most writing resulting in very thin marks or, at best, digging or building that offers little control in the z-direction.
Therefore, there is a need for a method for producing nanostructures that can meet or exceed the throughput of electron beam direct write systems.
There is also a need for a method for producing nanostructures that can achieve comparable resolution to electron beam systems at relevant throughputs.
There is also a need for a method for producing nanostructures that can be provided at lower capital tool costs.
There is also a need for a method for producing nanostructures that can provide perform in-situ metrology and repair.
There is also a need for a system for repairing and modifying, at the nanoscale, manufactured devices.